The servo gun includes one pair of electrode tips for spot welding. At least one electrode tip is a kind of welding gun, which is movably installed in a servo motor with a built-in encoder, and has an operation function to perform revolution control/torque control, thereby performing a position control or a pressure control of an electrode tip.
According to a conventional method of grinding an electrode tip of a welding gun, a pair of electrode tips are grinded by contacting both surfaces of a rotating cutter of a dresser for a predetermined time, e.g., 15 seconds. Thereafter, a grinding completion is determined by examining with the naked eye whether a front end surface of each electrode tip is grinded in a predetermined shape.
When grinding each electrode tip, however, it is demanded to grind each tip rapidly and clearly.